CAREER: Linking novel thermophiles with ecosystem function: Study of a model spring in Nevada

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The goal of this project is to characterize the unusual microorganisms that thrive in Great Boiling Spring (Nevada), and their role in this and other hot springs in the Great Basin by integrating chemical, microbiological and molecular biological studies. In most environments on Earth, the sun is the source of energy that sustains life. Some environments, however, are not directly dependent on light energy because it is unavailable or because physical conditions prohibit photosynthesis. For example, in hot springs and other thermal habitats where temperatures are consistently above 73 degrees centigrade, photosynthesis stops. At such high temperatures, organisms must gain energy by transforming inorganic compounds, a process called chemolithoautotrophy. Great Basin hot springs appear to be different from better-studied springs in Yellowstone National Park in that they seem to be dominated by different chemolithoautotrophic microbes. These particular bacteria are new to science. In this study, the relevant chemistry of the hot springs will be determined and used to calculate the energy available to microorganisms. It is predicted that the reactions that yield the most energy will be most important to the microorganisms in the spring. Second, these predictions will be tested directly by measuring microbial activities in the spring and indirectly by measuring chemical changes with depth in sediment cores. Evidence of microbe-mediated chemical reactions and their locations in the spring sediment will be evident in changes in chemistry. Third, the activities that were predicted and measured will be tentatively assigned to microbial species by combining genomic DNA sequencing methods with stable isotope chemistry. Fourth, the information will be used to drive attempts to cultivate important microorganisms in the laboratory so they can be studied in more detail. In summary, this project will allow us to better understand the foundations of life in hot springs, and expand our knowledge of the diversity of life on Earth.In addition to training undergraduate, graduate and postdoctoral researchers, this study will be conducted in coordination with a summer field course involving UNLV students working together with Native American high school students and teachers from the Pyramid Lake Paiute tribe. Students and teachers will participate in field and lab experiments designed to determine how stable Great Basin springs are on an inter-annual timescale including measurement of bulk chemistry and concomitant examination of the sediment microbial community. In addition, classes will include guest lectures and field trips led by guest scientists, geothermal engineers, Paiute elders, and anthropologists. It is anticipated that the course will stimulate Native Americans' interest in, and assist in management of their natural history heritage. Hot springs are important cultural and natural resources for Paiutes but they also represent potential sources of revenue from geothermal energy. Furthermore, it is expected that members of the Paiute tribe and UNLV students will each benefit by working together to understand the scientific and cultural importance of the region's hot springs.